1. Field of the Invention
The present invention relates to high resolution position measurement systems, and more particularly to sub-millimeter resolution time-of-flight radio location systems operating over a range of less than about ten feet.
2. Description of Related Art
There are a wide variety of position-sensing technologies available which rely on non-mechanical technologies, such as the following:
(1) Infrared or optical systems that employ TV cameras and complex video tracking algorithms; PA1 (2) Ultrasound systems; and PA1 (3) Continuous wave (CW) radio frequency fringe counting and phase measurements systems. PA1 (1) mounting a transmitter on the object; PA1 (2) transmitting from the transmitter a sequence of electromagnetic pulses; PA1 (3) detecting time-of-flight of the electromagnetic pulses from the transmitter to the receiver; and PA1 (4) processing the time-of-flight to indicate the position of the object.
The infrared or optical systems are very expensive and, therefore, are impractical for most commercial applications of position sensing. The ultrasound systems are quite inaccurate and unreliable. The CW radio frequency fringe counting and phase measurement systems suffer severe multi-path problems and ambiguities in the position-sensing data. None of these prior systems provide high resolution, and all are quite expensive.
High resolution, low-cost position-sensing can be applied to the interactive media arts, robotics, automotive occupant position sensing, digital surgery and a wide variety of applications where high resolution position sensing is desired.